Circadian Rhythms

In draft Research Domain Criteria, a Construct of an Arousal and Regulatory System

"Circadian Rhythms are endogenous self-sustaining oscillations that organize the timing of biological systems to optimize physiology and behavior, and health. Circadian Rhythms:

1. Are synchronized by recurring environmental cues;
2. Anticipate the external environment;
3. Allow effective response to challenges and opportunities in the physical and social environment;
4. Modulate homeostasis within the brain and other (central/peripheral) systems, tissues and organs;
5. Are evident across levels of organization including molecules, cells, circuits, systems, organisms, and social systems."